Any place on earth above about 25,000 feet . . . pretty sure
. . . that is if you mean within the next few thousand years.

Now for the 2nd part . . . Hmn gotta be some mountian somewhere fit for the task. I recommend the equatorial regions at progressively higher altitudes until you hit a sweet spot . . . I'm gessing about 16,000 feet . . . take oxygen with you . . . and a blankee